U.S. Amps US-1800 User manual

Category
Supplementary music equipment
Type
User manual
B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
OWNERS MANUAL
US-SERIES
PROFESSIONAL POWER AMPLIFIERS
US-1200
US-1800
US-3000
US-4000
THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
CONTENTS
Introduction ................................................... 3
Warnings and Safety Instructions ..................... 4-5
Features ........................................................ 5
Power Ratings at a Glance .............................. 6
US-Series Features .......................................... 7
Front Panel Controls ....................................... 8-9
Rear Panel Controls ........................................ 10-13
Protection ..................................................... 13-15
Setup ............................................................ 15-16
Connections ................................................. 17-18
Wiring ......................................................... 19
Specifications ................................................ 20
Warranty ...................................................... 21
Notes ........................................................... 22-23
Contact Information ........................................ 24
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B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
WELCOME TO THE B-52 FAMILY
Thank you for purchasing a US-Series Professional Power Amplifier.
At B-52, we believe in over-
building all of our products and the US-Series Professional Power Amplifiers are no exception. We took our time in de-
signing these stellar looking amps to outperform the competition on any stage, in the clubs and on the road. To achieve
studio quality audio reproduction we utilized low noise, low distortion circuitry and high current output stages.
We used oversized toroidial transformers and large filter capacitors to deliver super clean, fist pumping output even
when driving a 2 ohm speaker load. These amplifiers use the most reliable linear output devices which provide ultra low
distortion and a ruler flat frequency response. The US-Series is backed by our rock solid 3-year warranty and our com-
mitment to reliability known the world over.
It is imperative that you read and understand all of the warnings in this manual regarding proper usage, service
and safety. Failing to comply with any of these safety and operation warnings may void your warranty.
For more information about your US Series Amplifier, log on to: http://www.B-52Pro.com or call our customer
service support hotline (toll free) at 800-344-4384 or (+1) 323-277-4100.
Thank you again for choosing a US-Series Professional Power Amplifier.
Unpacking and Installation
Your US-Series Amplifier is neither complicated to install nor difficult to operate but you must take some time to
read this manual to ensure a properly wired installation. You will also need to become familiar with the amplifier’s
features and how to use it correctly. Please take care unpacking your amplifier; do not throw away the carton
and other packing materials. The original box may be needed to move your amplifier and will be required if it
becomes necessary to return the amplifier for service. Never place the amplifier near a radiator, in front of heat-
ing vents, direct sun light, excessive humid, dusty locations or near water. Connect your amplifier using the system
components described in this manual.
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THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
IMPORTANT INFORMATION
Please keep this instruction manual for future reference and for the duration of owning your
US-Series Professional Power Amplifier(s). Please carefully read and comprehend the instructions
inside this manual before attempting to operate the amplifier.
This instruction manual includes essential safety information regarding the use and maintenance
of the US-Series Amplifier. Take special care to heed all warning symbols and signs inside this
manual and those printed on the unit itself.
WARNING
TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE
THE AMPLIFIER TO
WATER OR MOISTURE. DO
NOT OPERATE NEAR ANY
WATER SOURCE
WHAT’S THE MEANING OF THIS?
e lightning ash with an arrow triangu-
lar symbol is intended to alert the user to
the presence of non-insulated “dangerous
oltage” within the products enclosure,
and may be of sucient magnitude to
constitute a risk of electric shock
1) Read these instructions.
2) Follow all instructions.
3) Keep these instructions.
4) Heed all warnings.
5) DO NOT turn on the amplifier before connecting all
other external devices.
6) Do not use the amplifier near water. Be extra cautious
when moving the amplifier during rain or while
transporting it over wet surfaces as water might splash
onto the unit.
7) Clean only with dry cloth.
8) Do not block any ventilation openings and operate in
accordance with manufacturer’s instructions.
9) Do not install near heat sources such as radiators,
stoves or other devices that may produce heat.
10) Do not defeat the safety purpose of the polarization or
grounding-type plug. A polarized plug has two blades
with one wider than the other. A grounding-type plug
has two blades and a third grounding prong. The wide
blade or the third prong is provided for your safety. If
the provided plug does not fit your outlet, consult an
electrician for replacement of the obsolete outlet.
11) Protect the power cord from being walked on or
pinched, particularly at the plug and the point where it
exits the amplifier.
WHAT’S THE MEANING OF THIS?
e exclamation point triangular symbol
is intended to alert the user to the presence
of important operating and maintenance
(servicing) instructions in the user manual
accompanying the Amplier.
!
12) Only use attachments / accessories specified by
B-52 Professional.
13) Unplug the amplifier during lightning storms and
when not in use.
14) Refer all servicing to qualified personnel. Servicing
may be required when the unit has been damaged
in any way such as when the power cord or plug is
damaged, liquid has spilled into the unit, the
unit has been exposed to moisture or rain, does not
operate normally, or has been dropped.
15) To reduce the risk of fire or electric shock, do not
expose the amplifier to rain or moisture.
16) Moisture can damage the amplifier and can cause
corrosion of electrical contacts.
17) Keep the unit out of extended or intense direct sun
light. No containers filled with any type of liquid
should be placed on or near the amplifier.
WARNING
Handle the power
supply cord with care.
Do not damage or
deform it as it may
cause electric shock or
malfunction when used.
Hold the plug attach-
ment when removing
from wall outlet. Do not
pull on the power cord.
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B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
1. READ INSTRUCTIONS – All the safety and
operating instructions should be read before this
product is operated.
2. RETAIN INSTRUCTIONS – The safety and
operating instructions should be retained for future
reference.
3. HEED WARNINGS – All warnings on the
amplifier and in the operating instructions should
be adhered to.
4. FOLLOW INSTRUCTIONS – All operating and
use instructions should be followed.
5. WATER AND MOISTURE
The amplifier should
not be used near water - for example, a bathtub,
washbowl, kitchen sink, laundry tub, wet basement, or
near a swimming pool, and the like.
6. CARTS AND STANDS – The amplifier should
be moved with a sturdy cart. An amplifier and cart
combination should be moved
with care. Quick stops, excessive
force, and uneven surfaces may
cause the amplifier and cart
combination to overturn.
7. INSTALLATION – Install in accordance with the
manufacturer’s instructions and local codes.
8. HEAT – The amplifier should be situated away
from heat sources such as radiators, heat registers,
stoves, or other appliances that produce heat.
9. POWER SOURCES – This product should be
operated only from the type of power source indicated
on the rating label. If you are not sure of the type
of power supply to your home, consult your product
dealer or local power company.
10. GROUNDING OR POLARIZATION – This
product may be equipped with a polarized alternation-
current line plug (a plug having one blade wider than
the other). This plug will fit into the power outlet only
one way. This is a safety feature. If you are unable to
insert the plug fully into the outlet, try reversing the
plug. If the plug should still fail to fit, contact your
electrician to replace your obsolete outlet. Do not
defeat the safety purpose of the polarized plug.
11. POWER CORD PROTECTION – Power-supply
cords should be routed so that they are not likely to be
walked on or pinched by items placed upon or against
them, paying particular attention to the cord in cor-
respondence of plugs, convenience receptacles, and the
point where they exit from the amplifier.
12. CLEANING – The amplifier should be cleaned
only as recommended by the manufacturer. Clean by
wiping with a cloth slightly damp with water. Avoid
getting water inside the amplifier.
13. NON-USE PERIODS – The power cord of the
amplifier should be unplugged from the outlet when
left unused for a long period of time.
14. OBJECT AND LIQUID ENTRY – Care should
be taken so that objects do not fall and liquids are not
spilled into the amplifier through openings.
15. DAMAGE REQUIRING SERVICE – The
amplifier should be serviced by qualified service
personnel when:
A. The power-supply cord or the plug has been
damaged; or
B. Objects have fallen, or liquid has been spilled
into the amplifier; or
C. The amplifier has been exposed to rain; or
D. The amplifier does not appear to operate
normally or exhibits a marked change in
performance; or
E. The amplifier has been dropped, or the chassis
damaged.
16. SERVICING – The user should not attempt any
service to the amplifier beyond that described in the
operating instructions. All other servicing should be
referred to qualified service personnel.
17. VENTILATION – Slots and openings in the
amplifier are provided for ventilation and to ensure
reliable operation of the product and to protect it from
overheating, and these openings must not be blocked
or covered. The openings should never be blocked
by placing the product on a bed, sofa, rug, or other
similar surface. This product should not be placed in a
built-in installation such as a bookcase or rack unless
proper ventilation as per the manufacturer’s instruc-
tions have been adhered to.
18. GROUNDING – Always maintain reliable
grounding of the rack and all equipment installed in
the rack.
19. POWER – The power switch in your amplifier is
not all-pole AC switch. You must physically disconnect
AC power cord from either amplifier or AC outlet to
fully disconnect it from AC mains. Make sure you have
access to the power cord if you need to disconnect it in
case of emergency.
20. LIGHTNING – For added protection for this
product during a lightning storm, or when it is left
unattended and unused for long periods of time unplug
it from the wall outlet. This will prevent damage to the
product due to lightning and power-line surges.
21. REPLACEMENT PARTS – When replacement
parts are required, be sure the service technician has
used replacement parts specified by the manufacturer
or have the same characteristics as the original part.
Unauthorized substitutions may result in fire, electric
shock, or other hazards.
22. SAFETY CHECK – Upon completion of any
service or repairs to this product, ask the service
technician to perform safety checks to determine that
the product is in proper operating condition.
IMPORTANT SAFETY PRECAUTIONS
CAUTION: To reduce the risk of electric shock, do not
remove any cover. No user-serviceable parts inside. Refer
servicing to qualified service personnel only.
The lightning flash with arrowhead symbol within the equilateral triangle is intended to alert the use to the
presence of un-insulated “dangerous voltage” within the product’s enclosure that may be of sufficient
magnitude to constitute a risk of electric shock.
The exclamation point within the equilateral triangle is intended to alert the user to the presence of important
operation and maintenance (servicing) instructions in the literature accompanying this appliance.
To prevent electric shock, do not use a polarized plug with an extension cord, receptacle or other outlet unless the blades
can be fully inserted to prevent blade exposure.
CAUTION
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THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
POWER RATINGS AT A GLANCE
US-1200 US-1800 US-3000 US-4000
Rated Output Power STEREO BOTH CHANNEL DRIVEN
8 Ohms 210 watts 300 watts 500 watts 700 watts
4 Ohms 330 watts 475 watts 800 watts 1100 watts
2 Ohms 430 watts 700 watts 1200 watts 1600 watts
Rated Output Power BRIDGED MONO
8 Ohms 650 watts 950 watts 1600 watts 2200 watts
4 Ohms 850 watts 1400 watts 2400 watts 3200 watts
Both channels driven @ 1kHz, 1%THD
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B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
AMPLIFIER FEATURES
The US-Series features four professional heavy-duty power amplifiers, covering a wide range of
output power ratings. The models are US-1200, US-1800, US-3000 and US-4000. US-Series
amplifiers are built on a rugged, heavy gauge steel chassis with a sturdy aluminum front panel.
The amplifiers use advanced circuitry and a well-designed PCB layout to ensure quality sound
and enhanced reliability. Large aluminum heatsinks and an oversized toroidal transformer, com-
bined with comprehensive protection circuitry and variable speed fan(s) provide worry-free and
reliable operation in the most demanding environments.
• Compactsize-upto3200wattsintworackspaces
• Ruggedheavygaugesteelenclosurewithsturdyaluminumfrontpanelforstability
and increased longevity
• High-currenttoroidaltransformersforincreased2-ohmpoweroutput
• 21-positiongaincontrolknobsforconsistentsettings
• SelectableSTEREO,PARALLELMONOandBRIDGEDMONOmodesforexibility
• FrontpanelLEDdisplay:POWER,BRIDGEandPARALLELLEDsandSIGNAL,-20dB,-10dB,
0dB,CLIPandPROTECTLEDsforeachchannel
• Protection:Shortcircuit,outputcurrentlimiting,thermal,DCoffset,turnon/offmuting,
RF protection and circuit breaker
• Cliplimiterstoreducedistortionwithoutsacricingpeakperformance(defeatableon
US-3000/US-4000)
• Sub-soniclterstoprotectspeakersandincreaseheadroom(defeatable)
• BalancedcomboXLRand1/4”TRSinputconnectorsandlinkXLRoutputconnectors
• BothbindingpostsandSpeakon™outputconnectors
• Low-noisecoolingfanswithcontinuousvariablespeedandhighlyefcientfront-to-rear
forced air cooling design
• Replaceableopencellfoamairlters
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THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
FRONT PANEL CONTROLS
1
1
2 2
Opposite page
1. RACK MOUNTING POINTS
Points to bolt your amplifier into a rack.
2. AIR VENTS
US-Series amplifiers are cooled by two rear-mounted
fans (US-1200 has one fan) and open cell foam filters
mounted behind the front vents.
CAUTION: Never block the front or rear vents
and keep them clean at all times.
NOTE: Periodically clean the foam filters using a
vacuum cleaner to avoid dust from blocking the
vents. If the filters become too dusty, it may
decrease your amplifier’s ability to dissipate
and remove heat efficiently. If the filters become
toodustyandtoodifculttocleanexternally,you
can access the filters and remove them for
cleaning. Refer to the cleaning procedure later
in this manual.
3. BLUE ILLUMINATED STRIPS
These two blue illuminated strips glow when your
amplieristurnedON.
4. CHANNEL 1 AND CHANNEL 2
LEVEL CONTROLS
Use these 21-position detented controls to adjust the
output levels of Channel 1 and Channel 2. When
theLEVELcontrolsaresetfullycounter-clockwise,the
signal is attenuated by more than 80dB (marked -).
WhentheLEVELcontrolsaresetfullyclockwise,the
signalisampliedwithmaximumgain.Whenthe
LEVELissetfullyclockwise,theamplierproduces
itsratedoutputpowerata4Ohmloadwith+4dBu
(1.23Vrms)signalappliedtotheinputs.Alldetents
are marked in dBs showing the attenuation of
the output signal with reference to the fully
clockwise position.
NOTE:InPARALLELMONOmode,bothofthe
Channel1andChannel2LEVELcontrolsare
used to adjust the signal level for their respective
channels. The signal should be routed only to
the Channel 1 input in this mode.
NOTE:InBRIDGEDMONOmode,onlythe
Channel1LEVELcontrolisusedtoadjustthe
signal level. The signal should be routed only to
Channel 1’s input in this mode.
5. SIGNAL Indicators
ThesegreenLEDswillilluminateindicatingthata
signal is being received through the input and that
thesignalisbeingamplied.TherearethreeLEDson
eachchannel:SIGNAL,-20dBand-10dB.
6. CLIP Indicators
TheseredLEDswillilluminateattheclipping
threshold.IftheCLIPLEDslightfrequently,youare
overloading the amplifier, causing gross distortions
on the outputs. Heavy clipping is bad for both your
speakers and amplifiers and should be avoided.
3
3
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B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
Reduce the output volume using the specific channel’s
level controls until the clipping disappears or until the
CLIPLEDsashonlyoccasionally.
7. PROTECT INDICATORS
TheseyellowLEDsindicatethatthechannelisineither
PROTECTmodeorMUTEmode.Whenthechannel
goesintoprotectmodeitsoutputwillturnOFF.Thisis
to protect the speakers connected to that channel.
NOTE:TheprotectLEDwilllightwhenthe
heatsinkisoverheating.Oncetheaffected
channel’s heatsink cools down, the output signal
willautomaticallyresumeandthePROTECTLED
willturnOFF.Constanttriggeringofthethermal
protection indicates blocked vents, dusty air
filters, possible low load condition, or problems
with your speakers or cables.
NOTE: ThePROTECTLEDswillilluminatefor
about two to three seconds when the amplifier is
poweredONandtheywillfadeslowlywhenthe
amplierispoweredOFF.Thisindicatesyour
amplifier is going through a transition process
and the outputs are muted.
WARNING:IfthePROTECTLEDsilluminate
constantlyanddon’tturnOFF,evenwhen
the speakers are physically disconnected from
the amplifier’s outputs, this indicates a fault.
ImmediatelyturntheamplierOFF,disconnect
thepowercordfromtheACoutlet,andreferthe
ampliertoservicepersonnel.AuthorizedB-52
service centers are listed at www.B-52Pro.com
8. BRIDGE LED
ThisgreenLEDilluminateswhentheMODEswitchon
therearpanelissetintheBRIDGEposition.Usethe
Channel1LEVELcontroltoadjusttheoutputvolume
inBRIDGEMONOmode;theChannel2LEVELcon-
trol is inactive in this mode.
9. POWER LED
TheblueLEDwillilluminatewhenyouramplieris
turnedON.
10. PARALLEL LED
ThisgreenLEDillumiateswhentheMODEswitchon
therearpanelissettoPARALLEL.UsetheChannel1
LEVELcontroltoadjusttheoutputvolumeofChannel
1andtheChannel2LEVELcontroltoadjusttheout-
put volume of Channel 2, even though both channels
amplify the same signal connected to the Channel 1
input.
11. AC POWER SWITCH
UsethisswitchtoturnyouramplierONorOFF.
5
4
4
7
7
6
6
5
8
9
10
11
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THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
1. FAN(S)
Coolingfanswithvariablespeedcontrols.Airenters
the amplifier through vents located on the front alu-
minium panel. Do not block the front vents or the fans
on the rear panel of the amplifier.
2. INPUT CONNECTORS
Connect the input source to these electronically bal-
ancedComboconnectorsusingeitherXLRor1/4”
TRSplugs.The1/4”TRSandXLRplugarecong-
ured:Pin2(Tip)-hot,Pin3(Ring)-cold,andPin1
(Sleeve)–shield/ground.Werecommendusingbal-
ancedthree-conductorcables.Astereosignalshould
be connected to both the Channel 1 and Channel 2
input jacks for 2-channel (stereo) operation.
NOTE: Unbalancedtwo-conductor1/4”plugs
can also be inserted into these input Combo
connectors. But using unbalanced connectors
may increase noise and hum. See more
information about balanced and unbalanced
connectionsintheCONNECTIONSsectionlater
in this manual.
NOTE:ForBRIDGEDMONOorPARALLEL
MONOusetheChannel1inputjackonly.
3. LINK CONNECTORS
TheseXLRjacksareusedtosendasignaltoaseper-
ateamplier(chaining).TheLINKXLRjacksarecon-
nected in parallel to the input Combo jacks.
4. HPF (HIGH PASS FILTER) SWITCH
Use these slide switches to activate the built-in High
Pass filters. The HPF rolls off signals below 50Hz. This
improves the bass performance of most full range
speakersbyreducinguncontrolledandexcessive
speakerconemotion.EngagingtheHPFswitchwhen
using full range speakers makes more power avail-
able to the speaker’s rated frequency range, leading
to higher SPLs.
REAR PANEL CONTROLS
1
2
2
3
3
4
45 5
6
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B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
5. LIMITER switch (US-3000 and
US-4000 models only)
When the sound source signal is too high, the out-
put signal will distort. To prevent this, both channels
feature clip limiters to prevent gross distortions on the
outputs. It is recommended to avoid clipping but if
it does occur, the clip limiters will greatly reduce the
amount of distortion and stress on your speakers and
amplifier. It is recommended to keep these switches in
theONpositionasthiswillresultinbettersoundand
increase the life of your loudspeakers.
NOTE: The US-1200 and US-1800 amplifiers
have built-in limiters that are permanently
engaged for constant protection and optimal
performance.
6. BRIDGE / STEREO / PARALLEL SWITCH
Use this switch to change the amplifier’s operating
modetoSTEREO,BRIDGEDMONOorPARALLEL
MONO.SetthisswitchtotheSTEREOpositionfor
normal stereo, or 2-channel operation.
WhensettoPARALLEL,theinputsignalconnectedto
channel1isroutedtobothchannels.ThePARALLEL
MONOmodeisconvenientwhenrunningalong
mono signal cable to a remote power amplifier(s),
and then connecting speakers to both of the channels
inordertoreproducethesamesignal.InPARALLEL
mode the input of channel 2 is inactive and should
not be used in this configuration.
IntheBRIDGEDposition,themonoinputsignalcon-
nected to channel 1 is routed to both the right and
left amplifier channels, yet in this mode the speaker is
connected between the two channels’ hot outputs and
is not referenced to the ground. In this mode the chan-
nel 2 input is inactive.
NOTE:SeetheCONNECTIONSsectionlaterin
thismanualformoredetailsonPARALLEL
MONOandBRIDGEDMONOmodes.
WARNING:DONOTswitchtoPARALLEL
MONOorBRIDGEDMONOunlessyouhave
read and understood these connections and their
limitations as described later in this manual.
7. BINDING POST OUTPUTS
Use the binding posts to connect your loudspeakers
to the amplifier. Binding posts are a good option for
xedinstallationsorwhenyoudonothaveSpeakon-
fitted speaker cables. The high-quality insulated
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binding posts offer a variety of connection options.
Use speaker wires with stripped ends (do not strip
themmorethan½”or12.5mm),usingtheholeson
thebottomofthebindingposts.Ensurethatnopartof
thespeakerwireisexposedwhenconnectedtothe
bindingposts.Alternatively,youcanalsousespeaker
cablesterminatedwithstandardbananaplugs.Make
sure that no part of speaker wire or banana plugs are
exposedwhenconnectedtothebindingposts.
NOTE: US-Series amplifiers configured for use
inEuropeareprovidedwithpermanentplastic
inserts which prevent using banana plugs for
speaker connection. This is a safety measure
requiredbyEuropeansafetylaws.
NOTE:IntheBRIDGEDmode,theloudspeaker
must be connected using the two red binding
posts.Thepositive(+)wirefromtheloudspeaker
must be connected to the Channel 1 red post,
and negative (-) wire from the loudspeaker must
be connected to the Channel 2 red post, as
indicated on the rear panel just below the
binding posts.
WARNING:NEVERCONNECTspeakerswith
an impedance lower than the rated minimum
impedance of the amplifier. The lowest
impedanceinSTEREOandPARALLELmodesis
2Ohmsforeachchannel.Thelowestimpedance
inBRIDGEDmodeis4Ohms.NEVER
CONNECT2Ohmsratedloudspeaker(s)or
a combination of speakers to the amplifier in the
BRIDGEDmode.
NOTE:RefertotheCONNECTIONSsection
later in this manual for speaker wire connection
diagrams.
8. SPEAKON™ OUTPUT CONNECTORS
Use these speaker outputs to connect cables fitted with
Speakon™cableconnectors.US-Seriesampliers
have two connectors, one for each channel, to con-
nectSpeakon™ttedcables.The1-pinisconnected
totheground.The1+pinisconnectedtotheoutput
of each channel, which is an industry standard.
You can connect both channel 1 and channel
2 loudspeakers to the Channel 1 output connector.
To do this a quad speaker cable must be used. The
Channel 1 speaker should be connected to pins
1-/1+andtheChannel2loudspeakerisconnectedto
pins2-/2+.
You can use the Channel 1 output connector for
BRIDGEconnectionofyourloudspeakers(whenthe
amplierisinBRIDGEmode).Inthiscongurationthe
loudspeakersconnectedmustusethe2+pinofthe
connector for the loudspeaker’s ground connection
(NOTCONNECTEDTOTHEGROUNDOFAMPLI-
FIER)andpin1+forthespeaker’sHOTconnection.
REAR PANEL CONTROLS (cont.)
12
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NOTE:Matchthepindesignationsprintednext
to the output connectors on rear panel to ensure
proper connections.
9. CIRCUIT BREAKER
The circuit breaker protects the amplifier from faults
attheACsupplyandservesasprotectionwhenthe
amplifier fails.
Ifthecircuitbreakertrips,cuttingACpower
supply to your amplifier, it may indicate a serious
malfunction or failure. Wait for the circuit breaker to
cool before resetting it by simply pressing the reset
knob. If the circuit breaker repeatedly trips, especially
when there is no signal on the inputs or outputs, this
indicatesafailureofyouramplier.DISCONNECT
the power cord from the amplifier immediately and
contact an authorized B-52 Service Center.
There are rare instances when the circuit breaker acts
on a constant heavy overload with a very low imped-
ance load connected to amplifier, protecting your
amplifier against such improper usage. In such cases
you need to check and correct your load (loudspeak-
ers) to provide for the proper load impedance,
and/orreduceoutputsignal.
10. AC INPUT
IECconnectorfortheACpowercable.Connectthe
suppliedheavy-gauge3-pinIECpowercable.
NOTE:NeverdisconnecttheEARTHpinfromthe
ACconnection.Itwilldefeatsafetymeasures
used in your power amplifier and void the
warranty.
US-Series amplifiers feature comprehensive protection
circuitry that protects both the loudspeakers and the
electronics from malfunctioning. The protection is non-
intrusive, sonically transparent and does not affect the
soundunlessthereareextremeconditionsthatacti-
vate the protection circuitry.
ThePROTECTLEDsonthefrontpanelilluminatewhen
the protection is active during the power-up sequence,
when thermal protection is activated, or when there is
amalfunction.WhenthePROTECTLEDsareON,the
amplifier’s outputs are muted.
INITIAL POWER-UP: The protection circuitry will
activate for about two to three seconds from the time
youturnONtheamplier.Thespeakeroutputsare
muted during this period. If the amplifier is operating
normally, the protection circuitry will deactivate and
the amplifier will switch to operation mode.
NOTE:ItisnormalforthePROTECTLEDtofade
graduallyaftertheamplieristurnedOFF.
THERMAL PROTECTION:Excessiveheat-sinktem-
peratures will engage the thermal protection circuitry
to avoid damage to your amplifier. The speaker
outputwillmuteandthePROTECTLEDwillilluminate.
Thermal protection only engages on the channel
whichhastheoverheatingheatsink,excepttheUS-
1200 where both channels will be muted. The thermal
protection will automatically restore to normal opera-
tion mode automatically once the heatsink tempera-
ture drops to a safe level.
NOTE: If the thermal protection constantly
activates, check the impedance of your loud-
speakers and the condition of the air filters on
front of the amplifier. The loudspeakers
impedance must not be lower than what is
specified in this manual for 2-channel and
BRIDGEoperation.8Ohmsand4Ohmsspeaker
loadsperchannel(8Ohmsand16Ohmsin
BRIDGEmode)shouldnottriggerthethermal
protection circuitry if the air access is not
blockedandtheairltersareclean.2Ohms
speakerloadsperchannel(4OhmsinBRIDGE
mode) can cause the thermal protection circuitry
to activate occasionally. If this occurs, decrease
the signal level and consider reconthe speakers
connections to reduce the load on the amplifier
(forexample,donotconnecttoomanyspeakers
in parallel to the same channel).
NOTE:Makesurethereisadequateairaccess
PROTECTION
13
THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
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to the amplifier. Do not block the air vents on
the front and do not block the fans on the rear
panel.Makesuretheopencellfoamairlters
behind the vents on the front of the amplifier are
clean. If necessary, use a vacuum cleaner to
clean these air filters.
NOTE: If the air filter become too dirty, the
amplifier may not operate normally as air
circulating inside the amplifier may become too
hot, thereby triggering the thermal protection.
If you cannot properly clean the air filters
externallywithavacuum,removetheairlters
from the amplifier and clean them thoroughly.
ThisprocedureSHOULDbeperformedBYA
QUALIFIEDPERSONNELONLY!Disconnectyour
amplifier completely from its power source –
YOUMUSTPHYSICALLYDISCONNECTTHE
POWERCORDANDNOTJUSTTURNOFFTHE
POWERSWITCH!Removetheamplier’stop
cover and locate the plastic brackets, which
house the air filters. Push the two levers at the top
of these plastic brackets to access the foam
filters. Remove the foam air filters, clean them
thoroughly and then place them back into the
amplifier. Secure the filter by snapping the plastic
brackets back into place.
TRANSFORMER THERMAL PROTECTION: If the
power transformer gets too hot, the thermal switch in-
side the transformer will trigger and will disconnect all
of the secondary power. When this occurs, there will
be no output signals coming from the amplifier and
allLEDs,includingthePROTECTLED,willbeOFF.
Oncethetransformercoolsdown,powertotheampli-
fier will automatically restore. In normal conditions,
the transformer will not overheat. Thermal protection
of the transformer indicates abnormal use, such as
excessiveoperationataverylowimpedanceathigh
signal levels. In this case, check and reconfigure your
loudspeakers connection. Reducing the output level
can also help.
NOTE: If the transformer overheats and
the thermal switch disconnects the power from
the amplifier, it will take some time for the trans
former to cool down before power is restored. It
takes much longer for the transformer to cool
down compared to overheated heatsinks.
SHORT CIRCUIT: If the output is shorted because of
faulty wiring, the thermal circuitry will automatically
protect the amplifier and mute the output signals. If
this occurs, the load will disconnect. Check and cor-
rect the short wire condition.
DC VOLTAGE PROTECTION: If an amplifier chan-
nel detects a DC voltage at the loudspeaker output,
the protection circuitry will trigger and the amplifier
will go into protection mode. In normal conditions
there should not be a significant DC signal on the am-
plifier outputs. DC on the outputs indicates a serious
problem with the amplifier. In this instance, the ampli-
fier must be referred to qualified service personnel.
SUBSONIC FREQUENCY PROTECTION: Built-in
high-pass subsonic filters provide subsonic frequency
protection for each channel. This protection prevents
subsonic audio signals, which may sometimes be
present in the music program, from reaching your
loudspeakers. Limiting the subsonic frequencies in
the output signal improves the sound reproduction by
reducingtheexcursionofthetransducer’sconeatlow
frequenciesandpreventsexcessiveheatinginsideof
the amplifier.
NOTE: US-Series amplifiers also employ
switchable high-pass filters (HPF), which limit the
low frequency range to 50Hz when activated.
TurntheseHPFsONwhenconnectingfullrange
speakers to the amplifier. This will improve the
bass performance of most full range speakers by
limitinguncontrolledandexcessiveconemotion
due to the lowest of frequencies. Using HPFs with
full range speakers provides more power to the
speaker’s rated range allowing higher SPLs. You
maywanttoturnOFFtheHPFswhenusingthe
US-Series amplifiers with quality subwoofers.
CURRENT LIMITING PROTECTION: The output
stage of the amplifier is protected by current-limiting
circuitry. This circuitry is inactive under normal condi-
tions. It activates only when it senses a dangerously
highcurrentthroughtheoutputtransistors,forexam-
ple when a connected load has an impedance that is
too low, or when the output of the amplifier is shorted.
Current limiting protection engages only when it is
needed and is not indicated on the front panel. If
there is a constant over-current condition it will acti-
vatethethermalprotection.Inthiscase,thePROTECT
LEDonthefrontpanelwillilluminate.
CLIP LIMITERS: US-Series amplifiers have built-
14
B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
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in limiter circuitry for improved performance when
overloading.Thelimiteractivatesat“clipping”when
the output voltage reaches the power supply voltage
rails. Without limiters, the output voltage will grossly
distort if the signal elevates beyond this point. The
signalwaveformisattened(“clipped”),producing
excessivehighfrequencydistortionnotpresentinthe
originalsignal.Thismakesmusicsound“dirty”and
increases stress on the high frequency transducers,
significantly shortening their life span (most loud-
speaker manufacturers will not honor warranties if
highfrequencydriversare“burnt”duetoaclipped
signal overload). Clip limiters effectively solve this
problem by compressing the signal at clipping. US-
Series amplifiers use intelligent clipping circuitry to
protect both the loudspeakers and amplifier.
NOTE: US-1200 and US-1800 amplifiers have
a built-in limiter circuitry which is constantly
activated. The US-3000 and US-4000 amplifiers
haveanexternalswitchlocatedontherear
panel, which activates and deactivates the clip
limiters. B-52 recommends the clip limiter switch
onboththeUS-3000andUS-4000remainON.
YoumaychoosetoturnOFFthelimiterswhen
using the US-3000 and US-4000 to power
subwoofers.
SETTING UP YOUR US-SERIES AMPLIFIER
CLIP LIMITER: Clipping is the result of an amplifier running into a power supply limitation.
Themaximumoutputvoltagethatanyampliercanproduceislimitedbyitspowersupply.
Attemptingtooutputavoltagelevelthatexceedsthepowersupplyvoltagerailsresultsina
atteningeffectofthesignalcausingittoclip.Aclippedwaveformexhibitsseveredistor-
tions, making it sound harsh. The clip limiter detects this condition and reduces the gain to
minimize the amount of overdrive. To preserve as much of the program dynamics as possi-
ble,thelimiterreducestheaverageprogramleveluntilthepeaksbarelyclip.Eachchannel
hasitsowncliplimiterandyoucanswitchitONorOFF(onlyonUS-3000andUS-4000).
The clip limiter allows brief clipping which is not detectable to the ear. It activates when a
clip condition repeats, to avoid prolonged distortion. When driving full-range speakers, clip
limiting reduces the high frequency distortion caused by low frequency overload. It also
protectshigherfrequencydriversfromexcessoverdriveandharshclippingharmonics.
NOTE:YoumaywanttokeepthelimitersOFFwhenconnectingtheUS-3000and
US-4000 to power subwoofers.
HPF (High-Pass Filter): High Pass Filters (HPF) are also known as low-cut filters. HPFs
ontheUS-Seriesamplierscutoffsignalsbelow50Hz.Asaresult,bassreproductionis
optimized, since ultra-low frequencies, which most speakers cannot reproduce anyway, are
eliminated and more power becomes available for the reproduction of the remainder of the
music signal.
NOTE: You should set the filters to best suit the frequency response of your speakers as
somespeakersareparticularlysensitivetoover-excursion.The50HzltersontheUS-Series
amplifiers work well with most full-range speakers.
NOTE: FormostsubwoofersandinstudioapplicationskeeptheHPFintheOFFposition.
15
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B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
MODE SELECT:
STEREO MODE
InSTEREOmode,bothchannelsoperateindependently,withtheirrespectiveinputgain
controls. Signal at the Channel 1 input produces output at Channel 1, while the signal
at Channel 2 input produces output at Channel 2. The minimum load impedance for
STEREOoperationis2Ohmsperchannel.
PARALLEL MODE
WhensettoPARALLELmode,asignalappliedtoChannel1’sinputwillbeamplied
and appear at both of the Channel 1 and 2 outputs. The level control knobs will oper-
ateontheirrespectivechannels.Channel2’sinputisinactiveinthePARALLELmode.
ThePARALLELmodeiswell-suitedforapplicationswhenyouneedtofeedtwospeakers
withthesamesignalbuteachspeakerispoweredbyitsownamplierchannel.Mini-
mumloadimpedanceforPARALLELoperationis2Ohmsperchannel.
BRIDGED MONO MODE
Bridged mono mode combines both amplifier channels to make a powerful single-chan-
nelamplier.Onechannel”pushes”andtheotherchannel“pulls”thesignalequally,
doubling the voltage. When the voltage is doubled, the power is quadrupled if the
same impedance load is used.
InaBRIDGEmode,thesignalmustbeappliedtoChannel1’sinputonlyand
Channel 1’s gain control is used to adjust the signal level. The gain control of Channel
2isnotusedandinput2isinactiveinBRIDGEmode.
NOTE:MinimumloadimpedanceinBRIDGEmodeis4Ohms.Connectinga
lowerimpedanceloadtotheamplierintheBRIDGEmodemaytriggerthe
protection circuitry. In some instances it may cause severe damage to the amplifier,
which is not covered by the warranty.
WARNING: MAKESURETHEIMPEDANCEOFTHESPEAKERSCONNECTEDIN
ABRIDGEMODEARENOTLOWERTHANSPECIFIED!!!
WARNING: Do not connect two 4 ohms subwoofers in parallel in BRIDGE mode,
as the total impedance halves in such a parallel connection. The total impedance
will be 2 ohms, and will cause constant overheating and distortion of amplifier. It
willalsocauseconstanttriggeringoftheACcircuitbreakerandcoulddamage
your amplifier.
NOTE:IntheBRIDGEmodeaspeakerisconnectedtobothofthechannels’
outputs and is not connected to the ground of the amplifier on both ends.
DONOTATTEMPTTOGROUNDYOURSPEAKER!
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US SERIES AMPLIFIERS
CONNECTING YOUR SPEAKERS
Stereo Mode
Parallel Mode
Bridged Mono
A
or
B
or
+
_
B
+
_
A
5-Way Output Binding Posts
A
or
+
_
B
+
_
A
5-Way Output Binding Posts
A
+
_
Bridged / Mono
5-Way Output Binding Posts
17
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THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
Stereo Mode
Parallel Mode
Bridged Mono
A
or
B
or
+
_
B
+
_
A
SPK+ to PIN 1+
SPK- to PIN 1-
SPK+ to PIN 1+
SPK- to PIN 1-
+
_
B
+
_
A
SPK+ to PIN 2+
SPK- to PIN 2-
SPK+ to PIN 1+
SPK- to PIN 1-
A
or
+
_
B
+
_
A
SPK+ to PIN 1+
SPK- to PIN 1-
SPK+ to PIN 1+
SPK- to PIN 1-
+
_
B
+
_
A
SPK+ to PIN 2+
SPK- to PIN 2-
SPK+ to PIN 1+
SPK- to PIN 1-
A
A
or
+
_
Bridged / Mono
SPK+ to PIN 1+
SPK- to PIN 2+
18
B-52 US Series Professional Power Amplifiers - Instruction Manual
THE BEAUTY OF POWER
US SERIES AMPLIFIERS
WIRING
There are multiple ways to connect a US-Series ampli-
fier to other audio equipment. The US-Series features
balanced inputs and link outputs, which allows you to
connect both balanced and unbalanced signals.
For speaker connections, you can use either binding
postsorSpeakon™connectors.
NOTE: Use speaker wires with the lowest
gauge available. The thicker the speaker wires
are, the less output signal you will lose.
19
UNBALANCED 1/4” CONNECTOR
BALANCED 1/4” CONNECTOR
SPEAKON
TM
OUTPUT CONNECTOR
NOTE: For connections of unbalanced sources
viabalancedcables/plugs,theringand
sleeve have to be bridged at the TRS plug.
THE BEAUTY OF POWER
B-52 US Series Professional Power Amplifiers - Instruction Manual
US SERIES AMPLIFIERS
US-1200 US-1800 US-3000 US-4000
Rated Output Power STEREO BOTH CHANNELS DRIVEN @ 1KHZ, 1%THD
8 Ohms 210 watts 300 watts 500 watts 700 watts
4 Ohms 330 watts 475 watts 800 watts 1100 watts
2 Ohms 430 watts 700 watts 1200 watts 1600 watts
Rated Output Power BRIDGED MONO @ 1KHZ, 1%THD
8 Ohms 650 watts 950 watts 1600 watts 2200 watts
4 Ohms 850 watts 1400 watts 2400 watts 3200 watts
Input Sensitivity 1.23 Vrms (+4 dBu) for full power @ 4 Ohms
Input Impedance 30K ohms Balanced/15K ohms Unbalanced
Frequency Response 0/-0.5dB: 20Hz - 20kHz; 0/-3dB: 5Hz - 60kHz
Signal to Noise Ratio Better than 100dB (20Hz - 20kHz)
Distortion (SMPTE-IM) Less than 0.03%
Output Circuitry AB AB H H
Cooling Continuosly variable speed fan, front to rear
Protection Short circuit, thermal, current limit, DC offset, AC current inrush,
RF protection, subsonic, turn on/off muting
Connectors Input: Combo female XLR & 1/4” TRS jack. Link: Male XLR
Output: Both 5-way biding post and Speakon
TM
Controls Front: Power on/off switch, volume controls for each channel
Rear: Mode switch (stereo / parallel / bridge), HPF on/off,
Limiter on/off (US3000/4000)
Indicator
Power, parallel, bridge. Each channel: Signal, -20dB, -10dB, clip, protect
Power Requirements 115/230V 60/50Hz factory configured
AC current consumption Both channels driven at 4 Ohm load, at 115Vac (for 230V divide by 2)
Typical level, 4.5A 6.3A 7A 9.6A
1/8 power pink noise
Severe level, 7A 9.6A 14.8A 19.8A
1/3 power pink noise
Dimensions (W x H x D) 19” (482mm) x 3.5” (88mm) x 17.2” (438mm)
Net Weight 28lb (13kg) 35lb (16kg) 43lb (19kg) 49lb (22.3kg)
SPECIFICATIONS
20
* Specifications are subject to change without notice.
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U.S. Amps US-1800 User manual

Category
Supplementary music equipment
Type
User manual

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